The Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia in Guatemala reported a degassing event on Mount Pacaya, a 2552 m high active volcano roughly 30 km to the southeast of Guatemala City, on Tuesday November 2017, the latest in a series of such events that began around the beginning of the year. This began at about 8.00 am local time, and produced a small plume of gas and steam, which was accompanied by several audible explosions. On Tuesday 28 November the Institutio reported a series of Strombolian eruptions (eruptions consisting of regular explosions throwing lava bombs, incandescent cinders and small stones and ash a few hundred meters in the air) on the volcano, accompanied by a lava flow that ran about 30 m down the northwest flank of the volcano.
Lava flow and crater incandescence on Mount Pacaya. Le Chaudron de Vulcain.
Mount Pacaya is one of Central America's most active volcanoes, having erupted at least 23 times in the last 500 years. It is located 30 km southwest of Guatemala City on the rim of the ancient Amatitlán Caldera, a 14 by 16 km structure that was last active in the Pliocene, between 5.3 and 2.5 million years ago. The volcano forms a massif on the rim of the older caldera, comprising the Cerro Grande Lava Dome, the eruptive MacKenney Cone, and the Cerro Chino Crater, which was last active in the nineteenth century. Pacaya is visible from Guatemala City, and its frequent small Stombolian Eruptions (ejections of lava bombs and incandescent ash) make it a popular tourist attraction.
The approximate location of Mount Pacaya. Google Maps.
The volcanoes of Guatemala, and Central America in general, are fed by the subduction of the Cocos Plate beneath the Caribbean Plate along the Middle American Trench, which runs roughly parallel to the southwest coast of the isthmus. As the Cocos Plate sinks into the Earth, it passes under Central America, which lies on the western margin of the Caribbean Plate. As this happens it is heated by the friction and the heat of the planet's interior, causing the sinking plate to partially melt. Some of the melted material then rises through the overlying Caribbean Plate as magma, fuelling the volcanoes of Central America.
Diagrammatic representation of the subduction of the Cocos Plate beneath the Caribbean Plate along the Middle American Trench. VCS Mining.
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